This invention relates generally to filter assemblies and, more particularly, to various embodiments of a filter assembly configured for acoustic damping for use in compressors such as oxygen concentrators and other medical applications in the home care medical equipment industry.
Oxygen concentrators are commonly used in the care of respiratory patients, particularly, in the home care environment, to provide sufficiently high purities of oxygen to the patient without using high pressure tanks or liquid oxygen. Oxygen concentrators utilize ambient atmospheric air as their source of oxygen in conjunction with an absorption system such as one or more molecular sieve beds to separate oxygen from the other gases found in the air and to provide that oxygen in concentrated form to the patient. Atmospheric air typically includes approximately 80% nitrogen and 20% oxygen. Nitrogen is absorbed by the absorption system and is retained therein until subsequently purged.
Typically, atmospheric air is drawn into an oxygen concentrator from the ambient environment. Such ambient air is then passed through a filter assembly to remove dust and other contaminants, and the filtered air is then pressurized by a compressor for introduction into the absorption system. Once the compressed air is introduced into the absorption system, the nitrogen is selectively absorbed and released to atmosphere leaving the residual oxygen available for patient use. The absorption system is then regenerated and made ready for the next cycle. Oxygen concentrators typically produce an oxygen concentration usually in the range of 90–95%.
Use of an effective filtration system for purging contaminants from any liquid or gas is always important for a multitude of obvious reasons. Properly and effectively filtering the incoming ambient air before it is compressed and introduced into the absorption system of an oxygen concentrator is likewise important because effective filtration not only improves the overall efficiency of the oxygen concentrator but it also improves and increases the oxygen concentration provided to the patient. Poor filtration of the incoming air also subjects the oxygen concentrator and its associated compressor to excessive wear from particles which contaminate the system thereby decreasing service life while increasing maintenance.
Routine maintenance also includes changing the filter assembly at some point in time when the filter is dirty and no longer functional within certain parameters. It is often difficult to determine when the filter assembly should be changed because the filter element is often times hidden and concealed within an opaque housing structure. As a result, such filters are often replaced at a predetermined regular time interval regardless of the actual condition of the filter element. This is not economical or efficient since, depending upon the type and amount of use of the oxygen concentrator, the filter element may still be operable and may still have additional useful life when it is replaced at the predetermined time interval. A better mechanism for identifying when the filter element should be changed is needed.
Still further, the type and size of compressor associated with an oxygen concentrator determines the overall oxygen flow rate capacity as well as the level of noise produced by the system during operation. In general, large compressors required for providing higher rates of oxygen can be quite noisy. Also, such oxygen concentrators are typically used at home, or in a hospital or nursing home type environment, where noise generation can be a problem. Despite the fact that efforts are made to insulate and dampen the noise for the compressor, the sound generated is often excessive. Noise attenuation is therefore always an issue.
It is therefore desirable to provide a filter assembly which improves the air filtration process to the absorption system of an oxygen concentrator or other compressor assembly, which includes means for determining when to change the filter assembly, and which includes means to reduce and dampen the overall noise level associated with the operation of an oxygen concentrator or other compressor assembly.
Accordingly, the present invention is directed to a filter assembly which overcomes one or more of the problems as set forth above.